package com.cskaoyan.controller.zyl_wxlogin;

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.Security;
import java.util.Arrays;

/**
 * 微信通讯加解密类
 */
public class WxAesUtils {


    /*public static void main(String[] args) {
        decryptData("bmdheU9pKVKVyJOH8CR3mqp4mEeKZ1YOuMsVxXJKjRdc47rolEoe85JKAVEWmP2hl4NZB66qxN/NHHGsy0PqCn7hS4cLKqTgERXcYO0dURt2JuLg1myhG+PYhi0AROwfJytGBv77u8yinmMfyyKx6lSegkqnlIJ6TBIDYe2LCvW3kRVDzNDeWT0hOaLiRI6n3TFQwI0b5Tiu48UbFTHDhAtJ6LaZY+wg+PdtrHDgjWtt46pinENV22GFt77a6iIhdT4GzaW7ln45HuENtzXJLR5yM7SwT2pxKMGEknJGJD3yf/DxnR6a8HpXrwxtXHJfDlUzNS+Af51fOS/Z52LpbtvRecoEz8KKUxJ9lpcK1HrO/RMw/iYf+ce1bu5VIpYyMjTNAoLdffZ7V0HGMrVJUGbQMqk7ZjdCk1eqMyPpuIOuektgKE7K5wHqeo3NVo7A",
                "6pOQ1+4ca2ATDaSg4gauVA==",
                "zzmYGLoLH548Vf0fdJHHvA==");
    }
*/
    public static String decryptData(String encryptDataB64, String sessionKeyB64, String ivB64) {
        String data = null;
        try {
            data = new String(
                    decryptOfDiyIV(
                            Base64.decodeBase64(encryptDataB64),
                            Base64.decodeBase64(sessionKeyB64),
                            Base64.decodeBase64(ivB64)
                    )
            );
        } catch (Exception e) {
            e.printStackTrace();
        }
        return data;

    }

    private static final String KEY_ALGORITHM = "AES";
    private static final String ALGORITHM_STR = "AES/CBC/PKCS7Padding";
    private static Key key;
    private static Cipher cipher;

    private static void init(byte[] keyBytes) {
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + (keyBytes.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(ALGORITHM_STR, "BC");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解密方法
     *
     * @param encryptedData 要解密的字符串
     * @param keyBytes      解密密钥
     * @param ivs           自定义对称解密算法初始向量 iv
     * @return 解密后的字节数组
     */
    private static byte[] decryptOfDiyIV(byte[] encryptedData, byte[] keyBytes, byte[] ivs) {
        byte[] encryptedText = null;
        init(keyBytes);
        try {
            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(ivs));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedText;
    }


}
